From Ohio History Central

In 1885, oil deposits were discovered in northwest Ohio. To excavate the oil, the Ohio Oil Company was formed in 1887. The company's primary purpose was excavation of oil, not the refining and marketing of the product. In 1889, the Standard Oil Company purchased the Ohio Oil Company. The Ohio Oil Company continued to operate, but it was now a subsidiary of Standard Oil. By the early 1890s, the Oil Ohio Company was producing fifty percent of all of the oil drilled in Ohio and Indiana.

Following the dissolution of the Standard Oil Company in 1911, the Ohio Oil Company had to seek new markets for the oil that it drilled. It continued to sell to companies that once were part of the Standard Oil Company. It also found new consumers, especially in the American West. In addition, the Ohio Oil Company also began to drill for oil in the American West, especially in the Rocky Mountains.

During the 1920s, the Ohio Oil Company also extended its operations to the refining of oil, with the firms purchase of the Lincoln Oil Refinery in Illinois. In 1930, the Ohio Oil Company also purchased the Transcontinental Oil Company and its Yates Oil Field in Texas. This was the largest oil discovery in the United States up to this point in time. Transcontinental Oil was selling oil and gasoline under the brand name of Marathon. In 1962, the Ohio Oil Company officially changed its name to Marathon Oil. In 1981, the U.S. Steel Company purchased Marathon Oil. The name Marathon continued to be used for many of the company's gas stations. In addition, U.S. Steel purchased several other oil firms. In 1998, Marathon purchased Ashland Oil, creating the Marathon Ashland Petroleum LLC.